During manufacturing of liquid crystal display, for guaranteeing product quality, it is normally needed to test for optical parameters (such as VT, RT, etc.) of the product. Currently, optical devices such as DMS9000 are normally employed for testing, and before testing some preparation is needed so as to connect detecting signal lines of the optical device to testing area of the liquid crystal screen, and connection way thereof is as shown in FIG. 1. Specifically, firstly coats silver adhesive 300′ on the testing area of the liquid crystal screen 100′, and then makes solder wire 400′, and fixes the solder wire 400′ by paper adhesive tape, and finally connects the detecting signal lines 200′ of the optical device to the solder wire 400′ by testing clip 500′. The above preparation before testing is very cumbersome, and after the preparation is finished, it can be ensured that during testing the circuits are completely conducting and correct, but on the contrary the phenomena such as open circuit and short circuit occur, and then the situations such as there is not testing data or the testing data is incorrect occur.